Sound modifier



July 31, 1945. c. HUENLICH SOUND MODIFIER Filed NOV. 10, 1942 3moentor Charles Hirer; [1H2 Patented July 31, 1945 UNITED STATES PATENT OFFICE- v 2,380,845 SOUND MODIFIER Charles Huenlich, Bloomfield, N. J., assignor to Thomas A. Edison, N. J a corporation Incorporated, West Orange, of New Jersey Application November 10, 1942, Serial No. 465,129

3 Claims.

Figure 3 is a horizontal sectional view taken substantially on the line 3-3 of Figure 2.

In Figure 1 there is shown an acoustical-type sound reproducing device I of conventional decontaining the higher sibilant sounds, these being the primary sounds imparting intelligibility to ones speech. On the other hand, the usual record materals have a surface noise characteristic which rises with frequency-i. e., wherein the higher frequency components have the higher magnitude. Typically, this record surface noise reaches a level comparable to that of the recorded signal in the higher frequency range above mentioned. There will however be variations, as between machines and different record materials used, in the frequency at which the signal and noise components reach comparable levels. Because of these relationships between the recorded signal and surface noise'levels, there has been a distinct need for a fine adjustable control of a particular character over the frequency response characteristic of dictation-transcribing machines, this being particularly so for the higher frequency range mentioned in order that there may be obtained the best balance between recorded signal and noise level to give the maximum accuracy in speech intelligibility.

sign, having a hollow circular casing 2 provided with a central tubular neck 3 at the top and with a depending lug 4 at the front. This casing is closed at the bottom, by a diaphragm (not shown) to form a sound chamber therewithin. Below the casing there is a weight 5 having a universal pivotal connection to the lug 4; the weight having a pivotal connection 6 on a vertical axis to a bifurcated arm I and this arm having a pivotal connection 8 on a horizonal axis to the lug. The weight 5 pivotally carries a lever 9 into one end of which there is mounted a reproducer stylus ID, the other end of the lever being connected by a link II to the diaphragm aforementioned. Under the influence of the weight 5, and of a torsional spring 5' between the lug 4 and arm 1-, the reproducer stylus is held in coaction with a record R, which may typically be a wax-like record of cylindrical form as is fractionally shown. Thus, vibrations imparted to the stylus by the record are transmitted to the diaphragm aforementioned, and the vibration in turn generates corresponding sound vibrations in the sound chamber of the reproducing device.

It is an object of my invention to provide an improved sound modifier that will fulfill the need above expressed.

Other objects are to provide improvements in structure and arrangement for sound modifiers of conventional design, which will permit the reproduction of speech recording with improved quality and intelligibility; and to provide an improved sound modifier which is especially adapted for use in connection with acoustical-type machines for transcribing dictation.

Other and allied objects of my invention will more fully appear from the following description and the appended claims.

In the description of my invention reference is had to the accompanying drawing, of which:

Figure 1 is an elevational view, with a portion broken away, of an acoustical-type reproducing device to which the sound modifier of my invention is applied;

Figure 2 is a vertical sectional view of my sound modifier; and

These sound vibrations are transmitted from the tube 3 of the casing 2 to a flexible tubing II which it will be understood connects to a suitable ear cap or head set not shown. Interposed between the fiexible tubing and reproducer I, however, is a-sound modifier l2 which is adjustable to different settings by a knob l3 at the top as is now explained.

This sound modifier-which in its general structural arrangement is of conventional design-comprises a tubular housing l4 which is retained to the tube 3 of the casing by a set screw I5. This housing has a reduced-diameter bore IS in its upper portion, as is shown in Figure 2, which has an outlet opening [1 at the side in communication with the flexible tubing H by way of a tubular extension l8 on the housing. Rotatably fitting the bore I6 is-a cylindrical valve member is which has a flanged head 20 at the top seating on the housing Hi; this flanged head is covered by a knurled insulating piece to form the knob 13 aforementioned. To the lower end portion l9' of this cylindrical valve member there is keyed a washer 2! which isheld to the valve member by a, nut 22. This washer slidably engages a shoulder 23 within the housing to retain the cylindrical valve member in place. The valve chamber 24 extending from the i openings 25 increasingly Hand ' noise, as'to obtain animproved-aocuracy member is thus rotatable by-the knob II but its rotation is typically limited to an angular movement of about 180 by a stop pin I! provided on the knob it, which stop pin engages a suitable slot provided in the wall of the housing II as is shown in Figure 2.

This cylindrical valve member has a central bottom to near the top'thereof and leading from this chamber at a small distance from the top thereof, is a series of graduated openings 25 which are movable selectively into tion, with the side outlet opening II by turning the valve member relative to the housing ll. There may, for example be provided five of'these openings within a 180 angular interval about the valve member, the succeeding ones of which. roceedin in a alignment, or into registracounterclockwise direction about ment, the chamber 24 is extended well above the graduated openings 2!, and this upper portion of the chamber is filled with a thick cylindrical body 29 of sound-damping material. I find for example that com pith is a very suitable medium for this damping body. As so provided, it is found that the.sound modifier enables an operator to obtain a much more desirable tonal balance of speech reproduction, with a. less apparent surface noise and an improved intelligibility.

While the embodiment herein shown is a preferred one of my invention, it will be understood that I intend no unnecessary limitation of my invention thereto, for the same is subject to the valve member, have increasingly larger crosssectional areas, as is shown in Figure 3. By selectively setting the knob ll one or another of the is placed into registration with the outgoing tube is, from the reproducer i by way of the central chamber 14 and that selected opening to the tubing II. By moving a larger or smaller one of the openings 26 into registration with the outlet tube is, the volume of sound ton from the reprcducer is increased or decreased; in addition, there is obtained a frequency discriminating action in the sound tra on from the reproducer, which is of the character of attenuating sounds, relative to the high-frequency sounds, as smaller ones of the openings)! are brought into registration with the side outlet opening. The change in modification fromone setting to the next is however not discontinuo but gradual, tor the internal diameter of the outgoin tube is is equal substantially to the displacement, along the periphery of the valve, between centers of successive ones of the openings 25, and will thus bridgeadiacent openings when the valve is midway between settings.

It is in practice also found desirable to provide sound modifiers such as is obovedescribed with a leak vent. This venting case through a hole member, there valve member for between these holes when the valve member is adjusted to its different angular positions.

Sound modifiers of the form have proven to be very beneficial. in enabling the operators of transcribing machines to so adiust the tonal qualit and sound volume of reproduction', particularly-in relation to-the record surface transcription. I have found though that the-operation of these modifiers for the particular purpose herein oo'nsidered may be markedly improved by very simple means. This improvement is had ply by providing ing medium within the sound chamber II. of the modifier, particularly in the chamber above the nings 25, the damping medium begraduated ope portion of this ing rovided in eflect as a wall chan iber. For instance, as a preferred embodiand sound will be communicated the. low-frequency in' spe angular adjustment changes and modifications without departurev from the scope of my invention, which I endeavor to express according to the following claims.

I'claim:

1. In a sound modifier of the character described: a tubular housing having a sound inlet opening at one end. and a sound outlet opening in side wall thereof; a valve member closing the other end of saidhousing member and formwithin the housin member said valve member being rotatably mounted in said housing member and cooperating with said outlet opening to open and close the same upon of the valve member; and a sound-absorptive material lining a wall portion of said sound chamber, said material being exposed to the sound waves in said chamber, for

, direct sound absorption, and thearea of exposure of said material being above described the same in all adjusted positions of said valve member.

2. A sound modifier foracoustical-type reproducingphonographs adapted for transcribing dictation, comprising a housing member having inlet and outlet openings, an adjustable valve member in' said housing member having a chamber therein in communication with said inlet opening of the housing, said valve member having a' series of graduated openings leading from points in said chamber at a distance from the closed end thereof, said graduated openings being selectively registerable with said outlet opening by an adjusting of said valve'member; and a body of damping material 'atthe closed end portion of said chamber beyond said graduated openings, said damping material having a substantial surface thereof exposed within said chamber for direct sound absorption.

3. In a sound modifier including a housing member having inlet and outlet openings: the combination of a hollow valve member adjustably mounted in said housing member for controlling the {ransmission of sound from said inlet to said out et openings; means providing leak venting from within said valve member to the outside in each adjusted position of the valve member; and sound-damping means in said valve member, said damping means being placed outsound absorption.

CHARLES HUENHCH. 

